Study On The Polymorphism And Expression Pattern Of CAST Gene In Pig

Cast gene was considered to be a candidate gene which relate to meat traits. In this study, we detected the microsatellite locus diversity in the second intron of CAST gene in five pig populations and the SNPs located in the exon 9 of CAST gene in six pig populations. Meanwhile the expression pattern of CAST gene was investigated in longissimus dorsi of Mashen and Large White pig by RTFQ-PCR. Our objective was to obtain some statistics about CAST gene in longissimus dorsi of mashen pig.There was a microsatellite locus in which the core sequence was composed with -GT-base in the second intron of CAST gene. Five pig population (Mashen pig, Shanxi Black pig, large white, Landrace, Duroc) were detected in the microsatellite locus about the second intron of CAST gene. Five alleles (A: 171bp, B:179bp, C:185bp, D:191bp) were found in pig population including 227 samples. B allele was the protogene in Mashen population (gene frequency:0.6310), D allele was the protogene in Shanxi Black population (gene frequency:0.6389) and Duroc population (gene population:0.5143). Ten genotypes were found in total pig population, Most of the genotypes were homozygote in large white population (Ho: 0.7037) and Landrace population (Ho:0.6667); but Mashen population (He:0.5476) and Shanxi Black population (He:0.6111) were mainly composed with heterozygote.A total of 416 pigs from Duroc, Large White, Landrace, Jinfen White, Shanxi Black and Mashen were used to detect the polymorphisms within exon 9 of the CAST gene by PCR-SSCP. Seven haplotypes of A, B, C, D, E, F and G were detected in the examined populations. A was the main haplotype in mashen population. A and B were the main haplotypes in Duroc. A, B, and C were the main haplotypes in large white and Shanxi black. B and C were the main haplotypes in Landrace and Jinfen White. Five transition mutations of T�', A�'G, C�'T, C�'T and C�'T were detected by cloning, sequencing and homologous comparison, which were located in the 37、150、167、193 and 256 of the amplified region. Two missense mutations were detected in coding region among five transition mutations. At the site of 193, threonine mutated to isoleucine, while at the site of 256, threonine mutated to methionine. Last, we analyzed the relation between haplotypes and body weight and size traits in Jinfen White populations by using GLM process and least square analysis. According to the resμLt, the different haplotypes distribution among body weight and size traits in Jinfen White pig didn’t reach significant level (P<0.05).Compared the difference about the expression abundance of CAST mRNA in longissimus dorsi between large white and Mashen pig in four days of age (60day,90day,120day,150day), we found out that it trended to increase from 60day to 90day then down at 120day about the expression of CAST mRNA in Mashen pig (male); In Mashen pig (female), it trended to constant from 60day to 150day. It trended to increase from 60day to120day then down at 150day in large white (male); In large white (female), it trend to increase from 60day to 90day then down at 120day. Totally, there were significant difference between Mashen pig and large white.